Stihl 026

[div_h]

Any idea how this would happen or is just because it did? Thank again for all your help guys!

[spudulike]

Any idea how this would happen or is just because it did? Thank again for all your help guys!

 

Casting weakness, cracked by removal at some stage, something else letting loose and damaging it - knackered clutch springs.......... No idea:lol:

[Rich2484]

What does the brake drum look like??

[agg221]

Any idea how this would happen or is just because it did? Thank again for all your help guys!

 

Looking at the pictures, I don't think this was a clutch spring failure. To go like this you need a big lump to come free and hit things - clutch spring failure tends to bind on. It also needs to move out of the operating plane of the clutch as otherwise it will just be held against the clutch drum by centripetal acceleration.

 

My guess is that either the central nut sheared first or one of the central tabs holding the clutch shoes. These would both leave large lumps of metal free. If it was the clutch shoe that broke free then it might have been held against the clutch drum but vibration and spring tension could soon pull it out of line. This is probably slightly more likely as the metal thickness is lower.

 

The failure is likely to be due to fatigue. Why? Possibly a small notch at a corner, due to poor pressing or forming, or maybe due to being a bit too cold when bent to shape.

 

Likelihood of recurrence? Pretty low I would say if used normally.

 

Alec

[div_h]

What does the brake drum look like??

 

Looks ok but think al just order 1 anyway plus a new bar,chain the list is getting bigger,

[div_h]

[Rich2484]

Looking at the pictures, I don't think this was a clutch spring failure. To go like this you need a big lump to come free and hit things - clutch spring failure tends to bind on. It also needs to move out of the operating plane of the clutch as otherwise it will just be held against the clutch drum by centripetal acceleration.

 

My guess is that either the central nut sheared first or one of the central tabs holding the clutch shoes. These would both leave large lumps of metal free. If it was the clutch shoe that broke free then it might have been held against the clutch drum but vibration and spring tension could soon pull it out of line. This is probably slightly more likely as the metal thickness is lower.

 

The failure is likely to be due to fatigue. Why? Possibly a small notch at a corner, due to poor pressing or forming, or maybe due to being a bit too cold when bent to shape.

 

Likelihood of recurrence? Pretty low I would say if used normally.

 

Alec

 

 

Hmmm not disagreeing but I have seen a fair bit of damage done before with just one spring breaking and getting stuck behind the clutch forcing the clutch plates out. The bad Grand Canyon behind the clutch looks like a spring has been forced into the metal.

 

Are the needle bearings any good. Will need some aswell if not.

[div_h]

[spudulike]

That sprocket looks knackered, could a loose chain have slipped around it under load and eventually smashed the clutch - it needs replacing!

[agg221]

Hmmm not disagreeing but I have seen a fair bit of damage done before with just one spring breaking and getting stuck behind the clutch forcing the clutch plates out. The bad Grand Canyon behind the clutch looks like a spring has been forced into the metal.

 

Are the needle bearings any good. Will need some aswell if not.

 

Agree the Grand Canyon looks like a spring gouge. I'd be surprised if that resulted in the central nut failing though.

 

Alec